Field of Invention
The present invention relates to a vibrating device, and more particularly to an ultrathin electromagnetic vibrating device and its manufacturing method, wherein a surround is added to replace a function of a damper, so as to change a thickness of a conventional electromagnetic vibrating device.
Description of Related Arts
It is generally known that a speaker is a common electromagnetic vibrating device, and the speaker is commonly called a “horn”, which is an electroacoustic device converting electric energy into acoustic energy. A manufacturing process of a traditional electromagnetic vibrating device comprises: gluing a T-yoke or a U-yoke; gluing a basket and a magnetic circuit; installing terminals; putting in a damper; plugging in a voice coil; and putting in a vibrating reed and a surround. Firstly, materials needed should be prepared, and then the electromagnetic vibrating device is made by hand, from top to bottom, inside and out. Wherein the damper, also called a spider, is a main element in a vibrating system of a cone electromagnetic vibrating device, the damper are corrugated rings made of cotton, silk, glass cloth, etc., which are impregnated with phenolic and hot-pressed into the corrugated rings. Main functions of the damper are as follows.
(1) The damper keeps the voice coil in a correct position in a magnetic gap. The damper has a large axial compliance, in such a manner that the voice coil is able to vibrate vertically in the magnetic gap. In a radial direction, the damper reliably restricts left and right movements of the voice coil, in such a manner that the voice coil is not in contact with a washer and the T-yoke;
(2) The damper provides a restoring force to the electromagnetic vibrating device as a supporter, and has an effect on a mechanical Q value, also called damping characteristic, of the electromagnetic vibrating device;
(3) The damper, a cone, and a voice coil suspension system codetermine a resonance frequency and a natural resonant frequency of the electromagnetic vibrating device; and
(4) The damper of the electromagnetic vibrating device plays a role of a buffer and a mechanical limiter.
Based on above functions of the damper, in the traditional electromagnetic vibrating device, an inner ring of the damper is fixedly connected with the voice coil, an outer ring surface of the damper is fixedly connected with a base frame of the electromagnetic vibrating device, thus, a thickness of the electromagnetic vibrating device is limited in some degree.
However, with a development of the society and a continuous improvement of people's living standard, people hope electronic products, such as LCD TVs, notebooks, computers, mobiles, to be thinner and thinner, meanwhile, people pay more attention to acoustic fidelities of the electronic products. But the thickness of the ordinary electromagnetic vibrating device used in the electronic products is limited by the damper. The damper and the surround are used to keep the voice coil and the vibrating reed in balanced strokes in the electromagnetic vibrating device. In the traditional electromagnetic vibrating device, an inner connecting surface of the damper is fixedly provided in a central position of the voice coil via glue, and an outer connecting surface of the damper is fixedly provided on the base frame of the electromagnetic vibrating device via glue, thus, a length of the voice coil and a thickness of the base frame are limited by the damper, the thickness of the electromagnetic vibrating device is further limited and is not able to meet demands that the electronic products put on the electromagnetic vibrating devices. Meanwhile, as time goes by, glues on the damper and the voice coil of the traditional electromagnetic vibrating device will age, or even degum, which will cause a change of the acoustic fidelity of the electromagnetic vibrating device or a scrapping of the whole electromagnetic vibrating device.